1. Field of the Invention
The invention relates to a nuclear power plant with a gas cooled high temperature reactor, and more particularly to a reactor with a spherical fuel element core and a prestressed concrete pressure vessel surrounding the high temperature reactor. The reactor cavity is clad with a liner and contains a plurality of heat exchangers, preferably steam generators for operational heat removal. At least two auxiliary heat exchangers for decay heat removal are also arranged in the reactor cavity. The prestressed concrete pressure vessel has a thermal protection system including a thermal insulating layer and a liner cooling system comprising a plurality of cooling pipes through which water flows and which, together with intermediate heat exchangers and cooling water pumps, a closed intermediate cooling loop used for the removal of the decay heat in case of an auxiliary heat exchanger failure.
2. Description of the Related Technology
U.S. Pat. No. 4,554,129 shows a gas cooled nuclear reactor installed in the cavity of a prestressed concrete pressure vessel. The heat generated in the reactor core is transferred to several heat exchangers located in the cavity above the nuclear reactor. No auxiliary heat exchangers are provided for the removal of the decay heat. Decay heat is removed by a liner cooling system made up of cooling pipes welded to the cavity liner inlet and return lines connected to the cooling pipes and a plurality of circulating pumps. Heat is transported from the reactor core to the liner cooling system by central pipes provided inside the heat exchanger and by shut-off valves closed in normal operation in a annular space bordering on the liner. A natural downward directed flow of heat is established in the annular space, so that all areas of the liner are exposed to the cooling gas.
DE-OS No. 33 35 268 shows a high temperature reactor with spherical fuel elements. Steam generators and blowers for operational removal of heat and auxiliary cooling systems for the decay heat removal in case of accidents are located together with the other components of the primary loop in the cavity of the prestressed concrete pressure vessel. The cavity is provided with a liner exhibiting a cooling system. This liner cooling system may be used for the removal of the decay heat, should the auxiliary cooling systems fail. It has also been proposed to conduct the decay heat to the liner cooling system by natural convection without coolant loss in case of accidents.
DE-OS No. 31 21 377 shows a liner cooling system for a prestressed concrete pressure vessel intended to house a nuclear reactor and containing an interior thermal insulating layer. The liner cooling system is redundant, i.e. it consists of several mutually independent water circulating loops.